The invention relates to a rotor of an electric machine, in particular a hydrogenerator, as is used in pumped storage plants, for example, with a rotor body which is constructed from laminated metal sheets and is held together by axial clamping bolts. Axial winding slots are arranged over the outer circumference of the rotor body, with a rotor winding being inserted into said winding slots and held therein counter to the action of centrifugal forces. The winding bars emerging axially from the rotor body and forming a winding head are protected from the effects of centrifugal forces by special supporting means.
In such machines, the winding head on the rotor is subject to extreme mechanical and thermal loads. The support of the winding head with respect to centrifugal forces can in this case take place by means of banding consisting of prestressed steel wire in combination with a solid integral steel ring. The complex fitting assists, however, the transportation dimensions and the weight limitation of the rotor result in limitations. For rotors of hydraulic prime movers with large dimensions, it needs to be possible to perform the assembly directly at an installation position in the power station. Furthermore, large solid steel rings impair the flow through the winding head and therefore cooling of said winding head.
Document DE 195 13 457 discloses arranging press fingers on the end laminations of the rotor body and providing a supporting ring comprising at least two rings which are spaced apart from one another in the axial direction and which are supported at their inner circumference on the hub, the rings being clamped together, in that section of the rotor body which is close to the axis, together with the press fingers with the first tie bolt which passes axially through the rotor body. In the section which is further from the axis, second tie bolts are provided, which pass axially through only said rings and clamp the rings together axially. Finally, third tie bolts are provided which pass radially through the winding head and act at least on the outer circumference of the outermost, when viewed axially, ring.
A large number of axially running, mutually aligned, half-closed slots are provided distributed in the circumferential direction over the outer circumference of all of the rings, into which in each case one straight edge provided with radially running threaded bores is inserted, with said third tie bolts being screwed into said threaded bores. This provides secure radial support which can be easily produced.
However, in this known arrangement, the axial thermal expansion of the winding on heating can result in the winding pressing onto the winding head bolts (the third bolts) and said bolts experiencing undesired and intolerable bending.
Document WO 2010/115481 proposes, for avoiding these problems, a dynamoelectric machine with a rotor body, a ring-shaped winding head, which is arranged axially next to the rotor body and coaxially with respect thereto, and a supporting ring, which is arranged radially within the winding head and coaxially with respect thereto, the winding head and supporting ring being connected to the rotor body in rotationally fixed fashion and the winding head and the supporting ring being clamped to one another in the radial direction by tension rods, which are passed through radial bores in the winding heads and in the supporting ring. The tension rods in this case act with their radially inner ends on the supporting ring and with their radially outer ends on the bearing blocks, which bear against the winding head. The clear widths of radial bores in the supporting body have an excess dimension in comparison with the diameters of the tension rods, and the bearing arrangement of the radially inner ends of the tension rods on the supporting ring and the radially outer ends of the tension rods on the winding head enables a limited tilting movement of the tension rods towards the radial direction. This is achieved in particular in that at least some of the ends of the tension rods are mounted by means of bearing blocks, which have a spherical bearing surface.
However, one disadvantage with this solution is that all of the tension rods need to be prepared individually for a tilting movement, which results in considerable design and fitting complexity.